It’s the end of November; marked in my calendar as ‘time for a long-term stability analysis of dried blood samples spiked with salbutamol’. One month earlier, I’ve created a set of dried blood samples to study the effects of long-term stability of such dried blood spots spiked with two concentrations of salbutamol (a medicine to treat asthma) and stored them at different temperatures; in a freezer, in fridge, in the lab and in an oven set at 40 °C. This experiment is part of a validation study I’m carrying out.
I’ve measured the salbutamol concentrations just after creating the set of blood samples and stored the rest of the set under the different storage conditions. Now it was time to analyse part of the stored samples to see any differences in concentrations. And of course, exactly the moment the GC-MS was available and set up for my research it was time for error messages again. After Etienne’s blog about programming frustration, Francisco’s coding trouble and Jessica’s experimental errors; it was my turn for GC-MS autosampler error messages.
By the end of the day I had processed my blood samples and placed them in the GC-MS autosampler ready to be analysed. The first samples ran ok, so I went home. After a workout I came back to the University to check the analyses. Everything was still working ok so I left the samples again to run overnight. The next morning when I came in I saw that the needle for injecting the sample into the GC-MS was bent… I checked how many samples were analysed correctly and it appeared the fault had happened quite quickly after I left the previous evening. I changed the syringe and checked the analysis a few times during the day. After a couple of samples, the same thing happened:(. The new needle was bent as well and not suitable for liquid injections anymore.
Since it probably wasn’t a coincidence the needle bent twice, I had to figure out what was happening each time I wasn’t looking. Besides that, I don’t have an infinite amount of syringes and they are quite expensive (£54 each), so it wasn’t an option to just replace the syringe again. After consulting some manuals and forums the most probable cause of the fault was that the bungees in the injector had lost their elasticity so I replaced them for new ones with Rebecca. I replaced the syringe again and put some test samples (with different caps, without and randomly positioned around the sample tray) to be sampled. After a whole set of test samples being sampled correctly I unscrewed and screwed all caps of my samples again very carefully to make sure they were aligned as perfectly as possible and placed them back in the tray to be analysed. I also replaced the needle again and checked if the first samples were running ok. They were, until I left for the lab for a while and came back after 15 minutes… A broken needle again:(. So I set up the test samples again with an old needle and watched it sampling like a hawk for 2 hours. Of course nothing happened, but I wanted to sleep a night over it before setting up needle no 4. Next morning when I came in, Rebecca had set up a ‘digital eye’ to watch every move the autosampler made.
(By playing the video you can get an exclusive 30 seconds impression of my ‘hawk job’ the day before)
After realigning the autosampler to make sure that it was in its optimal position and after many test samples, it was time for needle no 4 and attempt no 4 of trying to analyse my dried blood samples. Thirty hours later (17 mins each for each sample), it finally seemed the tablet had beaten the superstitious needle bending from happening.
Now all that’s left is to wait until next month when the second set of the samples has to be analysed! In the mean time I’ve changed the tablet setup to something suitable for December;
I’m looking into possibilities to include flasks with colourful liquids, but for now: Merry Christmas!